1. Technical Field
The present disclosure relates to intake manifolds for internal combustion engines.
2. Background Art
Intake manifolds for internal combustion engine are commonly formed out of a polymeric material. In an effort to reduce noise radiating from the surface of the intake manifold due to resonant frequencies set up at particular engine speeds, it is known to provide internal and external bracing on the surface of the manifold and to provide internal posts formed out of the parent material. To provide the desired noise reduction, the cross-sectional area of polymeric internal posts is such that it reduces the flow area within the intake manifold, thereby limiting the peak power of the engine. This issue is particularly important for naturally aspirated engine, i.e. those without pressure charging on the intake, such as provided by superchargers or turbochargers. It may be possible to increase the size of the intake manifold to overcome the drop in flow area due to the posts, but with a corresponding increase in overall size of the manifold, which increases cost and weight and complicates packaging. Furthermore, a larger manifold may require thicker posts or more posts, further exacerbating the situation. Even with a larger manifold, the posts may cause eddies to form in the flow field that lead to noise at particular frequencies and/or cause undesirable flow patterns in the engine intake.